Telephone system test circuits extending over two selection stages



Aug. 28, 1951 K. G. JOHNSON 2,566,063

TELEPHONE SYSTEM TEST CIRCUITS EXTENDING OVER TWO SELECTION STAGES Filed June 27, 1947 5 Sheets-Sheet 1 ml 8m tm 2n mk 3 P 2 i INVENT R KA GEORG JOHNSON mk wk \k Fig. 2

8, 1951 K. G; JOHNSON 2,566,063

TELEPHONE SYSTEM TEST CIRCUITS EXTENDING Y OVER TWO SELECTION STAGES Filed June 27, 1947 5 Sheets-Sheet 2 m mw N: am

H ENTOR fix L KARL 6320326 JOHNSON BY L) Q I" ATTORNEYS 1951 K. e. JOHNSON TELEPHONE SYSTEM TEST CIRCUITS EXTENDING OVER TWO SELECTION STAGES 5 Sheets-Sheet 5 Filed June 27, 1947 w t i8 3 6 nT+ H V M w! g m V m l. T+ 5 Mn 4 .mk k E N w mm W FL L L ma -1| III mm H. I 4 I M J3 NQ 1 K it gk 2% 2E RE 2Q R it w+ ma -1+ NM 4 6 I 2k Sm m bk wk P L m-| IL- 34 F F F- I Mk W wl Q4 l \NN I Ti .82 Tim tn atk SE 2Q 3Q mm 2% 5:5 i- .EHI... N w l n I III Qkfi NE J I' a W Fm W wk wg wt S2 1 MN I m: in I m I wi L q 2w HF W 3: Es J m 1 Q E QB 8E fink -85 -t 5.: PE 6.: 35 E :Q N5 3m w m RS N O N R N T am am we Aug. 28, 1951 Filed June 27, 1947 K. G. JOHNSON TELEPHONE SYSTEM TEST CIRCUITS EXTENDING OVER TWO SELECTION STAGES 5 Sheets-Sheet 4 PVI PVZ PV3 C4- C: l c2 C I312 I 331 I 332 I g: f 333 33 335 an r P63 Pc4 PCS 343 31,1, PC1 PC 2 P66 P67 P51 P82 P83 65 b4 be I PA 1 PA 2 PA 3 nb 2 --b I J 81 82 2 I 83 & a a3 a a a4 IN ENT R KfKRL GEORG JOHNSON ATTORNEYS 8, 1951 K. G. JOHNSON TELEPHONE SYSTEM TEST cmcuns EXTENDING OVER TWO SELECTION STAGES Filed June 27, 1947 5 Sheets-Sheet 5 N Q Sm mmw m od- R 8 MN Mm No N as R MN 0% w M J .G R m. c L M w K Patented Aug. 28, 1951 TELEPHONE SYSTEM TEST CIRCUITS EX- TENDIN G OVER TWO SELECTION STAGES Karl Georg Johnson, Stockholm, Sweden, as-

signor to Telefonaktiebolaget L M Ericsson, Stockholm, Sweden, 3. company of Sweden Application June 27, 1947, Serial No. 757,622 In Sweden August 1, 1946 2 Claims. 1

In automatic telephone systems consisting of small selectors switch steps are used, which consist of two or more selection stages, so-called primary and secondary selectors, combined by means of especial lines, called links or intermediate lines. When connecting through such a switch step it is necessary that that selector pertaining to a latter selection stage which is selected in a preceding selection stage, has access to at least one free line in that trafiic direction which the connection is intended for. The selection is usually made by means of registers and markers, whereby only one connection at a time may be set up through the switch step.

The present invention has for a purpose to set up a connection simply and swiftly from a calling line to a line within a called group of lines through a switch step being composed of at least two successive selection stages, whereby each of the selectors in a latter selection stage can reach only some of those lines which pertain to the called group of lines and only one communication at a time can be established under control of relay devices being individual for each selection stage, to which indicating wires from those selectors which can be used for the setting of the communication and from the lines of said group of lines are connected during the setting of the communication. This is achieved by the indicating wires of those selectors which pertain to said latter selection stage and which have access to the same lines, being connected together in a connecting point over a rectifier each, partly between themselves partly with indicating wires for those lines which may be selected by said selectors, and by circuits being closed over said rectifiers, connecting point and indicating wires to one of said individual relay devices for selection of a group of selectors, within which there is at least one free selector and which can reach at least one free line pertaining to the called group of lines, and for closing of further circuits over the indicating wires of the selectors in said group of selectors to another of said individual relay devices for selection of a free selector within the group, last-mentioned relay devices thereby being separated from said earlier mentioned relay devices of said rectifiers.

The invention will be described more closely by aid of the annexed drawings, Figures 1-7. In

Figs. 1-5 a switching operation is first shown passing only two selection stages.

Fig. 1 indicates a cross-bar switch GAI, the operating bars of which constitute primary selectors in a switch step comprising moreover two cross-bar switches GB! and GBZ, whose operatingor selecting bars constitute secondary selectors.

Fig. 2 shows besides the selectors GAI GBI and GBZ indicating wires and rectifiers for the secondary operating bars BIl-Bl2 and B2lB22 and their connection between themselves and with theindicating wires for a number of lines FIFI3, for which those circuits which are important for the invention, have been shown in Fig. 3.

Fig. 3 shows the indicating wires for lines pertaining to two traffic directions and connection relays for connection of the indicating wires to relay devices which are individual for the switch step.

Fig. 4 shows all individual relay devices which are necessary for the switch step.

Fig. 5 shows how the Figures 1-4 should be brought together.

Fig. 6 shows two switch steps, each containing two selection stages.

Fig. 7 shows how selections may take place through the two switch steps in Fig. 6 in dependence of each other.

In Fig. 1 three cross bar switches, GAI, GBI and GBZ are shown. A line L connected to an operating bar AI in the crossbar switch GAI has access to four intermediate lines ml-m4 connected partly to the selecting bars SAl-SA4 in the cross bar switch GAI, partly to the operating bars Bl l-B|2 and B2 l--B22, respectively, in the cross bar switches GBI and GBZ, respectively. The line L may over the intermediate lines mlm4 be connected to the lines FI'-Fl3, of which FIF1 pertain to a trafiic direction TI, and FB-FI 3 to another trafiic direction T2. The lines in both trafiic directions are grouped to gradings. In the trafiic direction Tl the line within the groups Fl-Fil and F3F4 should be selected at first hand and the lines F5-Fl not before all the lines FIF4 are busy. In the traffic direction T2 one selects Within the groups F8F9 and Fl 2-Fl 3 at first hand and thereafter among the lines FIOFI I. By help of Figs. 2-4 will be described below how a connection is set up between the line L and a line pertaining to the trailic direction T2. The connections from the line L are supposed to take place under control of a register not shown in the figures and a marker common to the Whole telephone plant, to which marker the relay devices shown in Fig. 4 are pertaining. The register is connected to the line L on calls over especial selectors, in a manner not important for the invention. When the register has received a sufiicient number of digits for the connection from the line L, for instance the relay VRZ in Fig. 3, is attracted by current over the wire t4. Relay VR2 pertains to the traflic direction T2. In Fig. 3 a relay VRI is also shown, receiving current over the wire t3 and pertaining to the traffic direction Tl. When relay VR2 attracts its armature, the contacts I l-l4 are closed. By connections from the line L or another line in Fig. 1 or 2 connected to the cross bar switch GAI a not shown circuit is closed over the wire tl to relay GAHl, which attracts its armature, thus closing the contacts ll -l4. Another relay GAH2, which is actuated by connections from other lines, is indicated to show how other primary selectors of the same kind as Gill may be connected. Because of especial relay devices, not shown in the figures, only one'relay GAI-Il or GAH2 at a time can be actuated. Line L is supposed to be connected to the contact strips on an operating bar in the cross bar switch GAl and may be reached by four selecting bars Sal-SM, each of which being connected together over links nil-m4 with its operating bar Bil-BIZ and B2lB22, respectively, in the secondary cross bar switches GBI and GB2. Each operating bar Bl l-Bl2 and B2 l--22, respective- .ly; is provided with a contact lllll02 and 2[H2ll2, respectively, which is actuated when the magnet of the operating bar attracts its armature. As long as the operating bar is free, its contact will be closed.

Contact's l ll4 are closed simultaneously with the" contacts ll-l4. The following circuits, which are partly converging, are thus completed:

1. From the positive pole of the exchange battery, called over" contact 14 and wire 02, through winding I on relay PCl in Fig.4, contact 3H, winding I on relay'PCZ, contacts 32l, 333-3 35 and 33 i, winding on r'elay P03, wire C2, contact ll, winding on relay MVZl, break contacts l lllll, i002 connectedin parallel for the lines Fl 2-El3, wire rl, rectifier -cl, connecting point Pl, rectiiiers cl l-el2 connected in parallel, contacts "ll-402, and lll2 to the negative side oi the exchangefbattery, called negative. If both the operating bars BH and Bl2 or both the IinesFIZ and PR3 are busy this circuit can of'course not be completed, as then both the contactsflflI-AQZ or both the contacts man-1on2 are. rske' 2. Contact 74, wirecl, winding I on relay PCI contact 37H, winding I on relay PC2, contacts 32l; 333-335 and 3,36 winding on relay P04, wire c 4,"contact l3, winding on relay MV23, break contact'connected in parallel for the lines F8F9, wirerE, rectifier e4,"rectifiers e2l e22 connected in parallel, contacts 2ill, 202 and l3l4 to negative. If both the operating bars B2| and B22 or both the lines Fl and F9 are busy, this circuit can not be completed.

"3 contact 14, wire cl, winding I on relay PC}, contact 3| l, winding II on relay PC2, contacts 3 22, 34 3--344 and 341, winding on relay P05, wire 03, contact 72, windin on relay MV22, contacts connected in parallel for the lines Flfl and Fl ll, wire r3, rectifiers c2, and c3, respectively, rectifiers el lel2 and e2le22, respectively, contacts l'l-l2 and l3-l4, respectively, tonegative. If all the operating bars Bi l, Bl2, B2l and B22 or both the'lines PH] and PH are busy, this ci'r'cuitcan' not be completed.

The relays PCI and PC2 are polarized relays with one middle position and two side positions. Inthe middle position contacts 3| l3l2 are not actuated.

Winding I is on both relays provided with a considerably greater number of winding turns than the winding II. The two windings I and lIQmagnetize the relay in the opposite directions. If therelay receives current through both the windings the winding 1 becomes deciding and contact 3l2 and 322, respectively, is broken. Wire i5 is in Fig. 4 a communication, which is not closed by connections from the line L to the trafiic direction Tl and T2, and thus relay PCl will always actuate contact 3l2. Relay PC2 actuates contact 322 and breaks the circuit according to 3 above if one of the circuits according to 1 or 2 above is closed. Hereafter one of the relays PCS 01' PC4 is operating, for instance P03, which breaks away PC3 and P05 and is self-held over contact 332. The relays PC5 and PCT pertain to circuits which are void of interest in above described switching operating. If none of the circuits according to 1 0r 2 above is closed, circuit 3 however being completed, relay PC2 will actuate contact 32l and relay PCB attracts its armature, breaks away relay PC! and is self held over contact 342. It is here supposed that last-mentioned case takes place, relay MV22 inFig; 3 thereby at tr acting its armature. Contacts 22l224 are actuated. Relay MV22 is self-held over contact 223. The following circuit is completed: contact 224, wire r4, winding on'i'elay FG in Fig. 2, to negative. Relay FG attracts its armature. Contacts 5i55 are closed. The following circuits are formed: contact 55, wire bl, contacts 93, 95, 96, 9| and 97, respectively, winding on relay PBl and PB2, respectively, wire b5 and b3, respectively, contact 5| and 53, respectively, rectifiers cl l-e l 2 and e2 l-e22, respectively, contacts lllllll2 and .2fll292, respectively, to negative over contacts lll2 and I3l4, respectively. One of the relays PBi or PB2 attracts its armature. Thus 'rectifiers e2 and c3 separate the relay MV22 from the relaysPB'l and PB2. Here is supposed that relay PBl attracts its armature, breaks away the relays PBZand PB3 and is self-held over contact 92 due to actuation of contacts ill- 94. The following circuit is completed: contact 94,'wire b4, "c'ontact'52, winding on relay GBHI, to negative. Relay GBHI attracts its armature. Contacts 3l36 are closed. The following circuits are completed: '-l-, contacts 82, 85, 85 in Fig. 4, 84 and 81, respectively, winding'on relay'PAl and PA2, respectivelyfwire a2 and al, respectively, contacts" 33 and 34, respectively, lil and IE2, respectively, and II and I2, respectively. One Of the relays PM or PA2 attracts its armature, for instance PAI. Hereby the relays FBI and PB2 are separated from relay PAl by the rectifiers ell and el 2. Contacts 8l-84 are actuated. Relays PA2 and PA3 are broken away. Relay PA l is self-held over contact 83. The relays'PA3' and PB3 pertain to circuits," which are: not necessary for the switching'operation described here; The following circuit is completed: negative, contact '8l, wire a3, contact 32, the winding on the selecting magnet for the selecting bar SAZ, to Furthermore current'is prepared for the operating magnet of operating'bar BIZ. The magnet of theselecting bar SA2 attracts its armature and the magnet of the operating bar Al l receives current over wire sl, which is connected 'tonegative at" connections from the line L. Thus line L is connected to link m2.

' Simultaneously with the selection of a free link m2 selection of a free junction line takes place through the following circuits'z'. contact 353,'354, 355 in 'Fig. 4, contact 35l and 356, respectively, winding on relay PVI and PV2, respectively, wire in and v2; respectively, contact 222 and HI, respectively, contact I003 and I004,

respectively, winding on relay FAlll and FAII,

respectively, to negative. One of the relays PVI or PV2, for instance PVl, attracts its armature. Contacts 35l353 are actuated. Relays PVZ and PV3 are broken away and relay PVI is selfheld over contact 352. Relay FAIO is actuated. Contact 1094 is closed. For the sake of simplicity only contact I005 pertaining to relay FA! has been indicated in the figure. In reality there I is a corresponding contact on all relays RAl-FAI3 being connected to the selecting magnet for that selecting bar SBl-SBH3, which pertains to the same junction line as the contact. The junction line Fill can bereached as well in the cross bar switch GBI as in the cross bar switch GB2 and therefore two selecting bars S33 and SB I3 pertain to the line Fl ii. From the contact [085 a circuit is closed over wire s2 through the lines on the magnets of the selecting bars SE3 and SBIS'. These magnets are actuated and is connected to the operating magnet of the operating bar B12, which is also actuated, and thus link m2 is connected to line FIG. Hereafter circuits are constituted, which are not indicated in the figures, for holding of the magnets of the operating bars All and B12, interruption of the current over wires tl, s9 and t4, and for actuation of relay FBIU, whose winding is indicated in Fig. 3. Contact I003 breaks the current of relay FAIi], contact I085 is opened and the current through the magnets of the selecting bars S33 and SBI 3 is broken.

The relay PV3 in Fig. 4 is necessary by selection to the trailic direction Tl, in which the three lines F5F1 are constituting a group. If hereby the relay MVl2 attracts its armature in the same manner as has been described above for relay MV22, relay PV3 becomes connected to the relay FAT of the line F1 over wire 03 and contact l2l. The selection among the links nil-m4 becomes the same as has been described above, but other selecting bars than SB|SBI4, shown in Fig. 2, will be connected.

In order to emphasize the applicability of the invention the Figures 6-7 have been drawn. Fig. 6 shows a number of connection paths through four selection stages for connection of a line L with a line ad pertaining to a traffic direction T. In the selection stage GA there are four links l4 to choose between and in the selection stage GB there are two links 5-6. In the selection stage GC there are four link (-10 and in the selection stage GD one of the lines ad is selected. Fig. 7 shows the circuits over the indicating contacts of the links and the lines, |-4, 56, '!ID and a-d. The wires tI-t2, t3t4, tS-tfi and fl-tlfi pertain to relay devices similar to those shown in Fig. 4. The connection is supposed to be controlled by registers and markers not shown in the figure, which, however, cause actuation of the relays A and G, whose contacts are shown in Fig. 7. Circuits from is hereby closed through a number of relays corresponding to for instance PVI-PV3 in Fig. 4, over the wires fl-tll, rectifiers e'l-elfl, contacts l--Hl, connecting point P3, retifiers eE-efi, contacts 56, connecting point PI and P2, respectively, rectifiers ele2 and e3-e4, respectively, contacts l2 and 3-4, respectively, to negative. If there is a free connection path a relay is actuated in the relay device connected to the wires ti-tlll. In dependence upon which relay is actuated a circuit is closed for one of the relays E or F and a relay device is connected over the wires t5t6, the rectifiers el-elll thereby separating the wires t!-tl0. The rectifiers e1el0 have foremost for a purpose to separate possible faults, for instance earth faults, on one of the contacts ad. Hereafter is selected between the wires t5 and t6, the relay D being actuated and still another relay device, which selects between the groups l2 and 3-4, is connected over the wires t3t$. One of the relays B or C is actuated and a relay device, which is connected over the wires tl and t2, selects one of the links l4. Each new relay device, which is connected, is separated from earlier selected or disconnected circuits by means of rectifiers; Thus possible faults are insulated and also a very great number of circuits may without inconvenience be connected together in the connecting point Pl-P3. If some link or line is met with in two dilferent cross bar switches, for instance I the lines FIB-Fl! in Figs. 2-3, further rectifiers el-e4 in Fig. 2 should be introduced to enable the indicating wire T3 to be connected to two connecting points PI and P2.

I claim:

1. In a telephone system, a calling line, a group of lines to be called divided into subgroups, a primary and a secondary selection stage each containing selectors for connection of said calling line to a line in said called group of lines, said subgroups appearing in difierent combinations in the multiple field of the selectors in said secondary selection stage, a contact for each line in said called group and a contact for each selector in said secondary selection stage, means affecting said contacts for marking a free or busy condition for the line or selector, 9. battery, common marker conductors, means operated from said marker conductors connecting all said contacts for lines belonging to the same subgroup in parallel between said common marking conductors and one pole of said battery, means operated from said common marking conductors connecting all said contacts for secondary selectors which can be connected to said calling line over said primary selection stage and in which the same combination of subgroups appear in parallel between the other pole of said battery and a connecting point separate for said combination, rectifiers, said rectifiers joining one of said marking conductors with each of said connecting points which represents a combination including the subgroup corresponding to the marking conductor, a chain of test relays, one of said test relays being connected in series with each of said marking conductors and selecting a subgroup containing at least one idle line to which the calling line can be connected.

2. In a telephone system as described in claim 1 means selecting one idle line within said selected subgroup, means selecting one group of secondary selectors which can reach said selected subgroup and means selecting one idle selector in said selected group of secondary selectors, all said means cooperating for setting a communication between said calling line and said selected line.

KARL GEORG JOHNSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,593,387 Clark July 20, 1926 1,922,237 Escott Aug, 15, 1933 

